1. Field of the Invention
The present invention relates to a method for supplementing amino acids in ruminant animals. More specifically, the present invention relates to a method wherein a rumen-protected feed additive composition comprising lysine and/or methionine is added to feed which is then fed to the ruminant prior to or after calving and continuing into the ruminant's lactation period. This method increases the digestible amino acids available in the feed and positively increases the milk production of ruminants who are fed the additive. The method also improves ruminant health and appetite.
2. Description of the Background Art
A ruminant is an animal which possesses a complex stomach consisting of four morphologically distinct compartments. These compartments are rumen, reticulum, omasum and abomasum. The former two are derived from the terminal portion of the esophagus, and only the latter two are considered to be a genuine stomach. After passing the first two compartments, the food is returned to the mouth. The rumen and the reticulum are fermentation compartments wherein Ophryoscolex diplodinium and Plectridium cellulolyticum are commensal, and the digestion of the feed (vegetable tissues) is conducted by cellulase, amylase, or cellobiose secreted by these microorganisms (digestive symbiosis).
In ruminant animals like cattle or sheep, there is a problem that occurs when a biologically active substance is, for instance, orally administered: a substantial part of the substance (e.g., proteins, amino acids, etc.) are decomposed to ammonia or carbon dioxide gas by microorganisms in the rumen, making it difficult or impossible for the animal to effectively utilize all of the administered proteins and amino acids contained in feed, etc. Thus, a ruminant only receives the benefit of a portion of the nutrients fed to it and loses a portion to the support and formation of rumen microorganisms. While the nutrients (proteins, etc.) contained in feed clearly contribute to a ruminant's sustenance, another source of nutrition for ruminants is the protein derived from those microorganisms in the rumen which are passed to the lower stomachs. Accordingly, it is important to maintain the microorganism population in the rumen in order to provide a constant source of this protein.
When special nutrients or drugs which must be absorbed or metabolized are administered to ruminants it is important to protect these substances from the environmental conditions in the first stomach: i.e., from decomposition by microorganisms and from the influence of weakly acidic or weakly alkaline pH, so that the substance can be maintained intact until it reaches the intended digestive or absorptive site. Namely, it is desirable that certain nutrients and drugs pass through the rumen to the omasum without being affected by microorganisms, digestion being conducted in the abomasum with the digested feed being absorbed by the small intestine. Nutrients, etc., protected in such a manner are well known in the art and are described in U.S. Pat. Nos. 4,976,976, 4,937,083, 3,619,200, 5,093,128, 4,837,004, 3,959,493, 4,842,863, 5,023,091, 4,957,748, 4,797,288, 5,064,665, and 5,244,669 and 5,227,166 all of which are incorporated herein by reference, and Japanese Laid-Open patents 59-66842, 58-175449, 56-154956, 63-317053, 60-168351, 59-198946, 02-027950, 02-128654, 02-128655, 03-05-8755, 03-155756, 03-155757, 04-079844 and 05023114 also incorporated herein by reference.
All proteins present in animals are constituted by combinations of more than 20 different amino acids. Among these, ten "essential" amino acids are not adequately synthesized in the animal body, and the animals must take them in. The amino acids constituting a certain protein are specific to the protein and cannot be changed. Accordingly, among the essential amino acids, the one(s) in least supply control the amount of protein(s) produced by the animal. When essential amino acids are lacking in the ruminant diet the ruminant's health, milk production, etc. are all negatively affected.
Since increasing the milk production of lactating dairy cattle is an ongoing challenge facing the dairy industry, many attempts have been made to provide a method for doing so. For example, Smith et al (U.S. Pat. No. 5,145,695) provide a method wherein a particular feed composition which delivers an improved balance of essential amino acids post-ruminally is fed to a cow. Nissen (U.S. Pat. No. 4,758,593) discloses a method wherein lactating domestic mammals are fed ketoisocaproate to improve the quantity and quality of milk produced. Kantor (U.S. Pat. No. 4,704,276) provides a method wherein lactating ruminant animals are fed certain antibiotics in order to increase lactation. Palmquist et al (U.S. Pat. No. 4,642,317) discloses a process of feeding ruminant animals increased amounts of fat while they are lactating in order to increase milk yield. Similarly, Mantha (U.S. Pat No. 4,175,121) discloses a process wherein essential nutrients, a methionine hydroxy analog, minerals, vitamins, proteins, Aspergillus oryzae and a buffer are fed to lactating cows to improve overall milk production. Rawlings et al (U.S. Pat. No. 4,225,620) describe a method wherein an alkali treated proteinaceous feed supplement is fed to ruminant animals so as to promote milk production. Finally, Cummins (U.S. Pat. No. 4,388,327) describes a process wherein the weight of milk produced by dairy cattle can be increased by supplementing the diets of cattle with .gamma.-methylmercapto-.alpha.-hydroxybutyric acid and its oligomers starting two weeks prior to the scheduled date of calving and for 112 days of production. All of the references described above are incorporated herein by reference.